Q: Does anyone have a solution to plugging of Titanium filter cloths (appears to be CaSO4)?

A: keep Ca, Mg, K out of generator liquor

Q: does anybody have a weightometer that works

A: Kamloops does

Alcell - Acrowood unit successful but sensitive to species

Crestbrook - two Milltronics units work well - used for chip bin level control

Crofton - Ohmart needs curves for different species, not too happy with it

Q: Going to MC one point injection in Do. What results have others had

A: Harmac -designing for one point Clo2

Skeena - one point for Cd, D , no impact for 2 point to 1 point, AOX went down

Northwood - one point - okay

Marathon - one point since started new system in 90

subcommittee on "best practices" should look at this

Q: When switching from hw to sw found when producing birch had to be much more aggressive, maple easy; what have other mills found ?

A: Norm Liebergott - must bleach harder for birch because more resinous material, need higher chlorine multiple, more aggressive extraction conditions

Jack Histed - hw delignifies in chlorination stage, little in exteraction compared to sw, so if don’t chlorinate well, can double caustic usage in extraction stage; use increased Cl₂ multiple

St. Anne- use 10-20% more chemicals for birch, also need pitch dispersant, practice minimum of six weeks of aging

Q: Is anybody bleaching in the high density? what residual to paper machine

A: Dupont - peroxide will react with nylon clothing and will shorten life - how well are you killing peroxide with so2, how much iron content (will catalyze peroxide decomp which will cause pulp strength loss)

Harmac - see Jim Oei at Squamish - peroxide hard on cleaner parts

Prince Albert - will get off grade because of dirt if you increase pH for bleaching, clean up piping and high density before trial

Howe Sound - ruined machine fabric with 20 ppm peroxide residual, went up to 100 ppm , ran 3 days, fabric ruined, now sour in cleaner area to positive SO₂ residual

Jean Bouchard - depends on different fabrics, some more sensitive to peroxide, others not

Dupont - nylons have additives that may provide some protectionarmacHarma

Q: sulphuric acid system - air pad, evacuate car to storage tank, get acid mist out of vent, safety hazard and corrosion problem; any similar experiences and solutions ?

A: Miramichi - same unloading system, no problem, 30 psi unloading; will send information

Prince Albert - damaged tank, unload at 15 psi, pressurized acid tank, popped top of tank

Dennis Owen - this safety report (prince Albert)is in earlier minutes (attached again in Appendix of these minutes)

Dennis Owen - get acid supplier to do safety audit - they may say vent should not be out top

CXY - with HCl recommend scrunbber, will get back about H₂SO₄, worst time is when it blows through, have run into this problem with customers who dont have a good scrubber

Q: who pumps acid cars

A: Tembec, Irving do.

Q: Tried kynar wires (both Albany and Johnson) for last couple of months, losing battle, frp deck lavalley washer, installed 2 wires, last two installed, pin seam smiles or frowns, each end of washer pulls out of groove, low friction between kynar and deck - any suggestions ?

A: Miramichi - may need a backing wire on Lavalley drums - we dont have, but heard from others

Rainy River - where do you store wire - if warm moist, may have trouble - twisting wire means not tight enough, does not shrink enough, cool dry area is best for storage

Howe Sound - 3 lavalley now, kynar wires, ordered Chime ring on end - has solved problem

Q: in-line kappa analyzer - who has one, what problems

A: Howe Sound - 91 installed BTG when new mill started up, took a year to get running, depends on furnish, each grade needs own calibration curve, they are tough to get started

Crestbrook - lots of problems on blowline, long time for I/M to learn to fix, important where you install

Q: is it good to use peroxide in the Eo stage ?

A: Norm Liebergott - if Eo works well, then may only get higher brightness, same kappa number, best place to put it is in E2

DeGussa - difficult to generalize, cost reduction ClO₂ savings reasons, need to look at it case by case

Fort Frances - peroxide to Eo essential to get brightness

Prince Albert - 10 years ago added peroxide at 4kg/t got 1 point higher brightness, didn’t give brightness increase to machine, so do not use it

Dryden - don’t use peroxide on hw, cost stayed the same

Cornwall - hw to 86 bright, low acm, peroxide works well, seeing some savings

Q: run to D1,D2 vat residuals, anyone run to J-tube residuals?

A: Irving - tests 3/4 up tube, target D1 0.3 gpl, 0.25 gpl D2 depending on mixer temp and time, in line sampler

Miramichi - similar to Irving, 0.24 in vat

Skeena - test both vat and upflow J-tube

Crestbrook - test at J-tube

Q: metals management acid vs DTPA vs EDTA - which is most effective

A: acid washes out metals but does not carry forward strength protection

EDTA chelates metals but loses effect in an alkaline stage

DTPA best choice (at pH 5-6) ; survives alkaline stages and preserves viscosity right through

Q: What temperatures are mills running LC Do stages at, and why ?

A: Avenor Thunder Bay - 65^oC

Howe Sound - 65^oC, Polarox, may be easier to control at lower temperatures

Histed - better at lower temp unless you can consume all ClO2

Liebergott - you get more AOX at lower temperatures, but will not experience pulp strength problems unless the temperature exceeds 80C

Q: Is anybody switching from thick stock pumps to MC pumps

A: Prince Albert - MC mixer and Ahlmixer together, works well, estimat 1-1.5 kg ClO₂/adt savings

Norm Liebergott - a mill found that when they push production then mixing becomes much more critical, especially at higher temperatures

Howe Sound - D1 stage changed from peg to mc mixer, thought it would work much better, found no difference, but recently found out that maintenance had removed the ring inside because the mixer kicked out, so will put back in and reevaluate

Q: has anybody used a brightness sensor to control peroxide to the Eop stage?

A: Canfor - brightness sensor on D2 tower of semi-bleached sequence to control peroxide to earlier P stage

Norm Liebergott - knows of a mill that does brightness testing on Eop stage to control ClO2 to next stage, good correlation to log of lignin content, but did not use as feedback to peroxide, but as feedforward to D1

Marathon - comment that brightness went up, but CEK number did not drop - found actually applying 0.7%, not 0.4%

Fletcher Challenge Canada, Crofton

Q: does anyone have a D1 stage brightness control that can be left days on end. Crofton’s lasts hours.

A: Tembec - upflow tower, could run well for a day, if hot water pH changes affects sensor - residual sensor 30 seconds after peroxide addition, good success on hypo, but not on ClO₂

Kamloops - it is a function of the quality of your instrument mechanic both brightness and residual are feedback

Prince Albert - Kajaani brightness and residual, 60%/40%, no problems, dial in remote set point, steady

Canfor - Kajjaani, no problems, startup on automatic

Northwood - went to do it on A line, supplier took a look in mixer with boroscope, saw air, supplier said would not work

Histed - at laTuque simplified bleach plant 0 residual on tower (D1 8 min, D2 60-120 min)

Q: Eop scrubber plugging with fibre - does anyone filter extraction filtrate before scrubber?

A: Rainy River - Kinney strainer

Owen - 9 people on survey said they used Kinney strainers

Howe Sound - switching from snowflake to globe packing so fibres will slip through

Harmac - tripac and tellerets, no problems

Marathon - tripac

Q: vessel entry to ??? - anyone check for CO?

A: essential to check for CO in high sub mills (B. VanLierop report)

Q: measure over 2000 ppm, venting to wl scrubber to 30 ppm, how can we prescrub?

A: Harmac - check for channeling

Owen - seal j-tube as if it was a ??? , but make sure you have a vacuum breaker on tower (Miramichi collapsed theirs)

HASimons - some mills put chilled water scrubbers on top of tower, water somewhere in process (St Felicien, Kamloops)

Elk Falls - pressure loop on line to towers, so eliminate the flow to the scrubber, so won’t blow the lid off the j-tubes

Q: tail gas scrubber disintegrating when running 2 gpm white liquor - ruined two fans

A: Norm - thiosulphate is corrosive - use oxidized wl

Northwood - destroyed 2 or 3 runners, now have titanium runners, problem could have been runners were in liquid. You run it without wl in winter, cl2 may attack fiberglass

Q: puffs in primary generator? ????

A: Owen - ??? "dancing waters" because you are cutting off the gas flow, it acts like a valve, causing high gas concentration

Q: Changing Do stage static mixer to dynamic mixer, bleach at 65C, what kind works - Ahlstrom? hi-shear mixer?

A: Owen - call Cosmopolis mill

Howe Sound - low AOX, pH went up, hastelloy mixer destroyed

Crofton - went with Ahlmix, not happy

Mackenzie - hi-shear - not happy, trialing now, may go back to static mixers

Q: any filtrate samplers on j-tubes?

A: Crofton has them on upflow towers

Q: What changes to scrubbing medium since the bleach plant scrubber survey 2 years ago?

A: Domtar - SO2

Northwood - SO2 to wl

Kamloops - no change

Howe Sound - changed to wl, control usng ClO2 gas measurement, works well

Dryden - weak wash

weak wash strained to remove precipitate

Q: D1 brightness control documented savings?

A: Kamloops - will dig it up

Crestbrook - paper in 88

Q: success stories on in-line pH meters?

A: Harmac - TBI in Eop at 175F work well, must be oriented correctly

Howe Sound - TBI work well, point down into stock

Prince Albert - tricky how you install - 30^o to pipe, otherwise gets damaged, TBI works well

Q: how to seal towers and vacuum protection

A: ???? - pressure indicator on top of tower,

Owen - vaccum breaks are designed for collapsing steam, not for draining towers

Q: What are mill ECF yields - in the lab we measure lower TOC, implying higher pulp yields?

A: HASimonsr - TOC is not a good measure of ???, because of more gas generation

Norm Liebergott - hard to measure yield increase, and difference is within experimental error

Q: Are any mills using on-line computer document control

A: HASimons - all documents are only on computer, including obsolete documents (RDS - talk to John Pope)

Miramichi - system 9000 out of Florida, evaluating it

Crofton - PC Docs, still working on it

Prince Albert - yes, but don’t know what it is